Friday August 23, 2019

Here’s Why Women are More Likely to Develop Alzheimer Diseases than Men

The new studies add more evidence and potential explanations for suspected variations between how men and women develop the disease

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FILE - Dr. William Burke goes over a PET brain scan, Aug. 14, 2018, at Banner Alzheimers Institute in Phoenix, Arizona. VOA

New research gives some biological clues to why women may be more likely than men to develop Alzheimer’s disease and how this most common form of dementia varies by sex.

At the Alzheimer’s Association International Conference in Los Angeles on Tuesday, scientists offered evidence that the disease may spread differently in the brains of women than in men. Other researchers showed that several newly identified genes seem related to the disease risk by sex.

Two-thirds of Alzheimer’s cases in the U.S. are in women and “it’s not just because we live longer,” said Maria Carrillo, the association’s chief science officer. There’s also “a biological underpinning” for sex differences in the disease, she said.

Some previous studies suggest that women at any age are more likely than men to develop Alzheimer’s. Scientists also know that a gene called APOE-4 seems to raise risk more for women than for men in certain age groups.

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Poor sleep can predict Alzheimer’s Risk in elderly. Pixabay

At the same time, women with the disease in its early stages may go undiagnosed because they tend to do better on verbal tests than men, which masks Alzheimer’s damage.  The new studies add more evidence and potential explanations for suspected variations between how men and women develop the disease.

Vanderbilt University researchers found differences in how tau, a protein that forms tangles that destroy nerve cells, spreads in the brains of women compared to men. Using scans on 301 people with normal thinking skills and 161 others with mild impairment, they mapped where tau was deposited and correlated it with nerve networks — highways that brain signals follow.

They found that tau networks in women with mild impairment were more diffuse and spread out than in men, suggesting that more areas of the brain were affected.

It’s long been known that women do better on tests of verbal memory — skills like recalling words and lists. University of California, San Diego, researchers found that women did better on these skills despite similar signs of early to moderate Alzheimer’s than men.

Using scans on more than 1,000 older adults, they found sex differences in how the brain uses sugar, its main energy source. Women metabolized sugar better, which may give them more ability to compensate for the damage from dementia and make them less likely to be diagnosed with it by tests that involve verbal skills.

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They found that tau networks in women with mild impairment were more diffuse and spread out than in men, suggesting that more areas of the brain were affected. Pixabay

“The female advantage might mask early signs of Alzheimer’s and delay diagnosis,” said study leader Erin Sundermann. “Women are able to sustain normal verbal performance longer,” partly because of better brain metabolism.

At the University of Miami, scientists analyzed genes in 30,000 people — half with Alzheimer’s, half without it — and found four that seem related to disease risk by sex. “One confers risk in females and not males and three confer risk in males but not females,” said one study leader, Eden Martin.

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Researchers don’t know yet exactly how these genes affect risk — or by how much. “Some of these look like they’re tied to the immune system and we know there are differences between males and females” in how that works, said another study leader, Brian Kunkle.

Seven other genes seem to have different effect on risks in men versus women. The researchers have a National Institute on Aging grant to do an international study on nearly 100,000 people to try to validate and extend the results. (VOA)

Next Story

Regular Exercise to Help Prevent Development of Physical Signs of Alzheimer’s

For the results, the research team conducted three studies--in the first study, the researchers examined 317 participants enrolled in the Wisconsin Registry for Alzheimer's Prevention

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Our research shows that in a late-middle-age population at risk for Alzheimer's disease, physically active individuals experience fewer age-related alterations in biomarkers associated with the disease. Pixabay

Regular exercise is not only good for memory as people age, but it also appears to help prevent the development of physical signs of Alzheimer’s, in those who are at risk for the disease, says a study.

“Our research shows that in a late-middle-age population at risk for Alzheimer’s disease, physically active individuals experience fewer age-related alterations in biomarkers associated with the disease, as well as memory and cognitive functioning,” said Ozioma Okonkwo, Assistant Professor at the University of Wisconsin.

For the results, the research team conducted three studies–in the first study, the researchers examined 317 participants enrolled in the Wisconsin Registry for Alzheimer’s Prevention, an ongoing observational study of more than 1,500 people with a history of parents with probable Alzheimer’s dementia.

In the second study, researchers studied 95 people, also from the registry, who were given scores called polygenic risk scores, based on whether they possessed certain genes associated with Alzheimer’s.

Exercise, Development, Alzheimer
Regular exercise is not only good for memory as people age, but it also appears to help prevent the development of physical signs of Alzheimer’s, in those who are at risk for the disease, says a study. Pixabay

Similarly, the third study examined MRIs from 107 individuals from the registry who were asked to run on a treadmill to determine their oxygen uptake efficiency slope, a measure of aerobic fitness.

Participation in the registry included an initial assessment of biological, health and lifestyle factors associated with the disease and follow-up assessments every two to four years.

All participants completed a questionnaire about their physical activity and underwent neuropsychological testing and brain scans to measure several biomarkers associated with Alzheimer’s disease.

The researchers compared data from individuals younger than 60 years with older adults and found a decrease in cognitive abilities as well as an increase in biomarkers associated with the disease in older individuals.

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However, the effects were significantly weaker in older adults who reported engaging in the equivalent of at least 30 minutes of moderate exercise five days a week.

“The most interesting part of our research is that we now show evidence that lifestyle habits – in this case regular, moderate exercise – can modify the effect of what is commonly considered a non-modifiable risk factor for Alzheimer’s, in this case, aging,” Okonkwo said.

“Overall, these studies suggest that the negative effect of aging and genetic risk on Alzheimer’s’ disease biomarkers and cognition can be lessened in physically active, older adults at risk for the disease compared with their less active peers.” (IANS)